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Leptocephalus energetics: An examina...

Bishop, Renee Elaine.

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Leptocephalus energetics: An examination of a unique larval developmental strategy.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	Leptocephalus energetics: An examination of a unique larval developmental strategy./
Author:	Bishop, Renee Elaine.
Description:	125 p.
Notes:	Major Professor: Joseph J. Torres.
Contained By:	Dissertation Abstracts International58-11B.
Subject:	Biology, Animal Physiology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9815422
ISBN:	0591665794

Leptocephalus energetics: An examination of a unique larval developmental strategy.
Bishop, Renee Elaine.

Leptocephalus energetics: An examination of a unique larval developmental strategy. - 125 p.

Major Professor: Joseph J. Torres.

Thesis (Ph.D.)--University of South Florida, 1997.

Leptocephali, the larvae of the superorder Elopomorpha, possess a developmental strategy that is unique among fishes. They grow rapidly by accumulating acellular mass in the form of glycosaminoglycans, instead of by large increases in cell number. Glycosaminoglycans serve as an energy depot for metamorphosis and as a gelatinous skeleton in the larvae. Besides their unique mode of growth, leptocephali are highly unusual in that for more than 230 years the trophic niche occupied by the long-lived larvae was unknown. Recent histological evidence has revealed that leptocephali consume larvacean houses and particulate organic matter. The present study examined the developmental strategy of leptocephalus larvae and their energetic requirements by determining the energy budgets for four species of leptocephali common to the Gulf of Mexico: Paraconger caudilimbatus, Ariosoma balearicum, Gymnothorax saxicola, and Ophichthus gomesii.

ISBN: 0591665794Subjects--Topical Terms:

1017835
Biology, Animal Physiology.

Leptocephalus energetics: An examination of a unique larval developmental strategy.
LDR:04751nam 2200337 a 45 001 934679
005 20110509
008 110509s1997 eng d
020 $a 0591665794
035 $a (UnM)AAI9815422
035 $a AAI9815422
040 $a UnM $c UnM
100 1 $a Bishop, Renee Elaine. $3 1258378
245 1 0 $a Leptocephalus energetics: An examination of a unique larval developmental strategy.
300 $a 125 p.
500 $a Major Professor: Joseph J. Torres.
500 $a Source: Dissertation Abstracts International, Volume: 58-11, Section: B, page: 5833.
502 $a Thesis (Ph.D.)--University of South Florida, 1997.
520 $a Leptocephali, the larvae of the superorder Elopomorpha, possess a developmental strategy that is unique among fishes. They grow rapidly by accumulating acellular mass in the form of glycosaminoglycans, instead of by large increases in cell number. Glycosaminoglycans serve as an energy depot for metamorphosis and as a gelatinous skeleton in the larvae. Besides their unique mode of growth, leptocephali are highly unusual in that for more than 230 years the trophic niche occupied by the long-lived larvae was unknown. Recent histological evidence has revealed that leptocephali consume larvacean houses and particulate organic matter. The present study examined the developmental strategy of leptocephalus larvae and their energetic requirements by determining the energy budgets for four species of leptocephali common to the Gulf of Mexico: Paraconger caudilimbatus, Ariosoma balearicum, Gymnothorax saxicola, and Ophichthus gomesii.
520 $a Metabolism was determined by analysis of oxygen consumption rate and the activities of three enzymes: citrate synthase, lactate dehydrogenase, and Na$\sp{+} $k $\sp{+}$-ATPase. Mass-specific oxygen consumption rates (Y, V$\sb{\rm O2}$ g WM$\sp{-1})$ (250-1200 uLO$\sb2$ g WM$\sp{-1} $h r$\sp{-1})$ declined precipitously with increasing wet mass (X, g WM) according to the relationship Y = a WM$\sp{\rm b}$ with b values ranging from $- $0 .3 to 0.8. Mass-specific oxygen consumption rates expressed versus wet mass were substantially lower than rates for other larval fish. However, dry mass-specific oxygen consumption rates were similar to those of other teleost larvae. Mass-specific enzyme activities (Y, activity WM$\sp{-1})$ decreased with increasing mass (X, g WM) following the equation Y = a WM$\sp{\rm b}.$ Slopes ranged from $- $1 .04 to $- $1 .23 for CS, $- $0 .805 to $- $1 .739 for LDH, and were $- $1 .23 for Na$\sp{+} $k $\sp{+}$-ATPase. The greatest changes in the slopes of mass-specific respiration and enzyme activities occurred in larvae less than 0.5 g WM, or during Phase 1a of leptocephalus development. As the leptocephali increased in mass, they did not increase substantially in metabolizing tissue.
520 $a Absolute ammonia excretion rates ranged from 0.21 to 0.65 umol NH$\sb3$ indiv.$\sp{-1}$ hr$\sp{-1}.$ The mass-specific excretion rates (Y, umol NH$\sb3$ g WM$\sp{-1})$ scaled significantly with mass (X, gWM) again following the relationship Y = a WM$\sp{\rm b},$ with the maximum change in slope occurring during Phase 1a.
520 $a Rate of growth was examined using otolith age estimates, RNA:DNA, and protein growth. Larvae, ranging from 7.8 to 240.0 mm total length (TL) were 4-111 days old. Growth rates fit multiplicative relationships (TL = a Age$\sp{\rm b})$ with slopes ranging from 0.37 to 0.96. Mean protein growth (% day$\sp{-1}),$ ranged from 16.1% to 37.3%. RNA:DNA values were low, with means for all four species ranging from 0.62 to 1.1.
520 $a Energy invested in somatic growth was examined by proximate and nucleic acid composition analysis. Protein, carbohydrate, and lipid increased with increasing total length and mass in a similar manner to other larval fish. Concentrations of the proximate components were different from conventional larvae. Carbohydrate concentration ranged from 2% to 25% of the ash-free dry mass. The transition from Phase 1a to Phase 1b was evident in the nucleic acid concentrations as a decrease in both RNA and DNA with increasing mass.
520 $a Comparison of the assembled energy budgets suggests that leptocephali require 50% less energy than conventional larvae of the same dry mass. Leptocephalus larvae grow rapidly with minimal energy expenditure, develop a substantial energy depot, and avoid the increased energy demands associated with increased mass by accumulating non-metabolizing tissues.
590 $a School code: 0206.
650 4 $a Biology, Animal Physiology. $3 1017835
650 4 $a Biology, Oceanography. $3 783691
690 $a 0416
690 $a 0433
710 2 0 $a University of South Florida. $3 1020446
773 0 $t Dissertation Abstracts International $g 58-11B.
790 $a 0206
790 1 0 $a Torres, Joseph J., $e advisor
791 $a Ph.D.
792 $a 1997
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=9815422